<template>
  <el-color-picker
    class="theme-picker"
    popper-class="theme-picker-dropdown"
    v-model="data.theme"
    :size="props.size"
  >
  </el-color-picker>
</template>


<script setup lang='ts'>
import { onMounted, ref,watch } from "vue";
import { ElMessage } from "element-plus";

declare var require: any
const version = require("element-plus/package.json").version; // element-ui
const ORIGINAL_THEME = "#409EFF"; // default color

const props = defineProps({
  default: {
    // 初始化主题，可由外部传入
    type: String,
    default: null,
  },
  size: {
    // 初始化主题，可由外部传入
    type: String,
    default: "small",
  },
});
const data = ref();
data.value = {
  chalk: "", // content of theme-chalk css
  theme: ORIGINAL_THEME,
  showSuccess: true, // 是否弹出换肤成功消息
};

const emit = defineEmits(['onThemeChange'])
 

onMounted(() => {
  if (props.default != null) {
    data.value.theme = props.default;
    emit("onThemeChange", data.value.theme);
    data.value.showSuccess = false;
  }
});
watch(() => data.value.theme,(newval,oldval) => {
     if (typeof newval !== 'string') return
      // 替换CSS样式，修改主题色
      const themeCluster = getThemeCluster(newval.replace('#', ''))
      const originalCluster = getThemeCluster(oldval.replace('#', ''))
      console.log(themeCluster, originalCluster)
      const getHandler = (variable, id) => {
        return () => {
          const originalCluster = getThemeCluster(ORIGINAL_THEME.replace('#', ''))
          const newStyle = updateStyle([variable], originalCluster, themeCluster)

          let styleTag = document.getElementById(id)
          if (!styleTag) {
            styleTag = document.createElement('style')
            styleTag.setAttribute('id', id)
            document.head.appendChild(styleTag)
          }
          styleTag.innerText = newStyle
        }
      }
      const chalkHandler = getHandler('chalk', 'chalk-style')
      if (!data.value.chalk) {
        const url = `https://unpkg.com/element-ui@2.15.12/lib/theme-chalk/index.css`
        getCSSString(url, chalkHandler, 'chalk')
      } else {
        chalkHandler()
      }
      const styles = [].slice.call(document.querySelectorAll('style'))
        .filter(style => {
          const text = style.innerText
          return new RegExp(oldval, 'i').test(text) && !/Chalk Variables/.test(text)
        })
      styles.forEach(style => {
        const {innerText} = style
        if (typeof innerText !== 'string') return
        style.innerText = updateStyle(innerText, originalCluster, themeCluster)
      })
      // 响应外部操作
      emit("onThemeChange", newval);
      if (data.value.showSuccess) {
        ElMessage.success("换肤成功！")
      } else {
        data.value.showSuccess = true
      }
  }
);

const updateStyle = (style, oldCluster, newCluster)=>{
      let newStyle = style
      oldCluster.forEach((color, index) => {
        newStyle = newStyle.replace(new RegExp(color, 'ig'), newCluster[index])
      })
      return newStyle
}
const getCSSString = (url, callback, variable) =>{
const xhr = new XMLHttpRequest()
      xhr.onreadystatechange = () => {
        if (xhr.readyState === 4 && xhr.status === 200) {
          [variable] = xhr.responseText.replace(/@font-face{[^}]+}/, '')
          callback()
        }
      }
      xhr.open('GET', url)
      xhr.send()
}

const getThemeCluster = (theme) =>{
  const tintColor = (color, tint) => {
        let red = parseInt(color.slice(0, 2), 16)
        let green = parseInt(color.slice(2, 4), 16)
        let blue = parseInt(color.slice(4, 6), 16)

        if (tint === 0) { // when primary color is in its rgb space
          return [red, green, blue].join(',')
        } else {
          red += Math.round(tint * (255 - red))
          green += Math.round(tint * (255 - green))
          blue += Math.round(tint * (255 - blue))

          red = red.toString(16)
          green = green.toString(16)
          blue = blue.toString(16)

          return `#${red}${green}${blue}`
        }
      }

      const shadeColor = (color, shade) => {
        let red = parseInt(color.slice(0, 2), 16)
        let green = parseInt(color.slice(2, 4), 16)
        let blue = parseInt(color.slice(4, 6), 16)

        red = Math.round((1 - shade) * red)
        green = Math.round((1 - shade) * green)
        blue = Math.round((1 - shade) * blue)

        red = red.toString(16)
        green = green.toString(16)
        blue = blue.toString(16)

        return `#${red}${green}${blue}`
      }

      const clusters = [theme]
      for (let i = 0; i <= 9; i++) {
        clusters.push(tintColor(theme, Number((i / 10).toFixed(2))))
      }
      clusters.push(shadeColor(theme, 0.1))
      return clusters
}
</script>

<style>
.theme-picker .el-color-picker__trigger {
  vertical-align: middle;
}

.theme-picker-dropdown .el-color-dropdown__link-btn {
  display: none;
}
</style>